The present invention generally relates to a retrieval service, and more particularly, to a method for searching multimedia data asynchronously and extracting the same.
According to generalization of a digital broadcasting service, research for a technology providing the customized broadcasting service under multi-channel and multi-media environment is actively progressed.
For example, TV-Anytime is an international standard, which allows a user to watch preferred contents by matching metadata with user's preference, based on metadata expressing description information of contents.
In TV-Anytime, the metadata include content-based description defined in MPEG-7 and information of the electronic program guide (EPG), and can make a user easily search and select contents preferred.
Standard of metadata is consisted of two parts. Part A defines schema which is a format to describe metadata, using the description definition language (DDL)(ISO/IEC 15938-2) based on MPEG-7. Part B which relates to metadata transmission includes a binary format for MPEG-7(MPEG-7 BiM)(ISO/IEC 15938-1), a fragmentation model, and a technique for encapsulation and indexing.
TV-Anytime Metadata are comprised of program description metadata and user description metadata.
The program description metadata is comprised of contents description metadata and instance description metadata. The program description metadata is associated with program using a content identifier called as the content reference identifier (CRID).
The content description metadata is generated by a content creator, and include a program title, genre, an abstract and a critic review. The instance description metadata are generated by a content provider and include location (such as broadcasting time, channel, URL, and so forth), usage rule and delivery parameter. Lastly, the user description metadata are generated by a user and include user preference, usage history and personal bookmark.
The TV-Anytime standard defines two types of metadata web services, which are well-defined behavior and remote procedure for input/output set, in order for two-way metadata web service through return pass.
In the web service description language (WSDL) standard based on the extensible markup language (XML), the remote procedure as described above is defined as the type of simple object access protocol (SOAP) operation. The remote procedure has the “get_Data( )” operation for metadata retrieval and the “submit_Data” operation for user description submission. For reference, the SOAP protocol is the XML communication protocol which can approach to an object in a distributed environment.
A request/response type used at the TV-Anytime metadata service is defined in name space of “urn:tva:transport:2002”, and the name space is provided as a verification tool for a variety of massages. Types defined in metadata specification and content referencing standard are referred in transport name space. Schema fragment is defined in the name space, and a name space provider is defined as “tns:” in the schema fragment. A perfect XML schema file is “tva_transport_types_v10.xsd”.
On the other hand, “get_Data( )” operation for data retrieval provide a client with the function for searching TV-Anytime data from a server for either a program or a program group. Examples for the function which the TV-Anytime metadata provider can provide by using the “get_Data( )” operation are as follows:                returning content referencing data for CRID using a CRID list;        returning TV-Anytime metadata for CRID by using a CRID list;        receiving an inquiry for particular metadata attribute, such as genre, actor and so forth, and returning a program related to the inquiry; and        responding to an inquiry for particular time or particular channel, and returning a corresponding program.        
More concretely explaining details with regard to behavior of “get_Data( )” operation, the client in TV-Anytime service transmits through network the SOAP request message (get_Data( )Request) to the metadata service server. At this time, “get_Data( )” operation fundamentally supports all kinds of inquiry types and provides broad range of inquiries for the metadata limitation condition. As followed by the transmission, the metadata service server returns result value for the SOAP request message by the SOAP response message (“get_Data( )” Response).
In summary, the TV-Anytime metadata client can perform metadata retrieval and server delivery of user's data through the “get_Data( )” and the “submit_Data( )” which are SOAP operations regulated in TV-Anytime.
FIG. 1 is a schematic view illustrating a multimedia retrieval procedure in TV-Anytime standard in accordance with the conventional technology.
As illustrated in FIG. 1, the multimedia retrieval method in accordance with the existing technology, a user send the retrieval inquiry to a server and then wait the corresponding result from the server. At this time, the user performs retrieval procedure through the “get_Data( )” operation, and the “get_Data( )” operation is defined as the SOAP message.
In addition, the multimedia retrieval procedure in accordance with the conventional technology is basically operated in the retrieval environment wherein status information requesting a retrieval inquiry is a text, and when status information of retrieval inquiry is a text, a problem for the multimedia retrieval method shall not occur.
However, when the retrieval inquiry status information includes contents like image or moving picture, processing time and resources needed for the contents increase much. Thus, if a session between a client and a server is maintained until retrieval result is received from the retrieval inquiry, much more resources of the client and the server are consumed and user's waiting time also much more increases in comparison with the waiting time for which status of retrieval inquiry is a text.
Furthermore, when the network session has been cut off during processing retrieval, there is a disadvantage to rerun the retrieval from an initial inquiry request that the inquiry has been begun.